Power excavator



w. FERRIS' POWER EXCAVATOR Aug. 15, 1933.

Filed Dec. 50, 1927 2 Sheets-Sheet 1 1N VENTOR l lLr zw FEEHI5 ATTORNEY.

Patented Aug. 15, 1933 PATENT? OFFICE rowan EXCAVATOR Walter Ferris, Milwaukee, Wis;

assignor to Bucyrus Erie Company, South Milwaukee, Wis., a Corporation of Delaware 1 Application December 30, 1927 Serial No. 243,738

6 Claims. (01; 214- 135) This invention relates to power excavators, loaders and the like and particularly to drive systems therefor.

One object of' the present invention is the 5 provision of an efficient drive system through which. the power derived from a single prime mover may be advantageously applied to effect the several motions characteristic of machines of the type mentioned, without sacrificing the flexibility of operation and ease of control ordinarily found in steam driven machines of this type.

,Other more specific objects and advantages will appear from the following description of an illustrative embodimentof the present invention.

In the drawings:

Fig. 1 is a fragmentary plan view of a power shovel equipped with a. drive system embodying the present invention. k i i Fig. 2 is a fragmentary side elevation.

The power shovel selected for illustration is of a well known type. It includes a truck frame 10, mounted upon creeping traction mechanism, conventionally indicated at 11, and carrying-a circular rack and track member 12, constituting the usual support for a revolving frameor platform 13. A pinion 14 fixed to a vertical shaft 15, journaled in the platform 13, meshes with the member 12 and coacts therewith to. swing the platform about a vertical axis in awell known manner. The platform carries the usual dipper supporting boom 16 and the usual dipper hoist drum 1'? controlled in the usual manner and operated through appropriate gears 18 and 19 from an internal combustion engine 20. mechanism is driven from the gear 19 through a conventional gear train 21 and shaft 22 under the controlof a clutch 23. The primary function, that of hoisting the dipper, is thus effected I from the engine 20 through direct mechanical connections which do not differ materially from standard practice and need not be further described; The auxilliaryfunctions, however, such as swinging and thrusting the dipper, are effected through an auxiliarry hydraulic system, prefer ably such as will now be described.

Thefhydraulic system shown is similar in many respects to that described in my copending Patent No. 1,793,438, issued February 17, 1931. ..i It includes a high pressure. hydraulic reservoir 24 into the bottom of which liquid is supplied from an appropriate variable displacement pump 25, against a resilient cushion of compressed air in the head end of the reservoir. The" pump shown is fully described in the copending Patent No. 1,793,198, to Walter Ferris and John The traction P. Ferris, issued March 31, 1931. In this in-' stance it is driven at constant speed through a shaft 26 and the displacement thereof is variable from zero to maximum in either direction by adjustment of a control lever 2'7. In normal operation it receives liquid through a pipe 23and discharges through a pipe.29 connected to the base ofthe reservoir 24. It also includes mechanism which responds to the discharge pressure in f pipe 29 to automatically reduce the displace ment whenever the discharge pressure exceeds a predetermined maximum. Since the eonstruction and operation of this pump are fully described in the patent hereinabovelast inen- H tioned a further or more detailed description thereof is deemed unnecessary. The pump serves tomaintain a working pressure within the res ervoir 24. When the pressure therein falls below 7 a certain degree the pump delivers liquid thereto at a rate determined by the setting of the lever 2'7 and as the pressure exceeds that degree pump displacement automatically reduces to thereby reduce the rate of flow in pipe 29 with a corresponding reduction in the power required to operate the same. i I i The pipe 28 leading to the pump is preferably supplied with liquid under low pressure from an appropriate low pressure reservoirBO. Liquid is supplied to the bottom of the reservoir 30, against an air cushion in the head end there- .of, by a gear pump 31 of a well known type. The

pump 31 receives its supply from an appropriate supply reservoir '32 through a pipe 33 and dis charges through a pipe 34in'to the base of reservoir 30. A pressure relief valve, conventionally indicated at 35 connected across the supply and discharge pipes 33 and .34, determines the-pressure in pipe 34 and consequently in the reser-. voir 30. Although the gear pump ordinarily 1 forms a part of the-main pump'25 it is here shown outside of the main pump casing and driven through an appropriate belt and pulley connection36 from the shaft .26. Valve con trolled drain pipes 37 and 38 permit the contents of the'high and low pressure reservoirs to be emptied into the supply tank when out of service. i l

" In the-hydraulic system shown two variable torque hydraulic motors 39 and 39' are employed for driving the swing mechanism and the dipper thrust or crowding mechanism, respectively. Both are ofthe type described in my copending patent first above mentioned. They are. driven by liquid supplied from the high pressure reser voir through a manifold 40 and branch pipes 41 and 4-1, respectively, and the liquid discharged by them is directed into the low pressure reservoir 30 through branch pipes 42 and 42', respectively, and manifold 43. An appropriate cut-01f valve 44 is preferably provided in each manifold 40 and 43 to be closed when the shovel is not in use. The operation of each motor is regulated and controlled by a rock shaft 45-45 through which the displacement and consequently the torque of each motor is varied in a manner described in said first mentioned patent. Rock shaft 45 is actuated and controlled .by an appropriate hand lever 46 fixed thereto, and rock shaft 45' is placed under the control of a hand lever 46 loosely mounted on shaft 45 and connected to shaft 45' through appropriate linkage 47. I

The motor 39 drives the shaft 15 through a conventional gear train comprising a pair of bevel gears 48 and 49 and a pair of spur gears 50 and 51 to swing the platform 13 in either direction under the control of lever 46; and motor 39" drives the usual. shipper shaft (not shown) through appropriate means such as a sprocket and chain connection 52 to thrust or retract the dipper under the control of the le ver 46'.

From the foregoing it will be noted that in the drive system shown the hoist drum 17 is direct- 1y driven from the prime mover 20, so that practically the entire power output thereof is available for peak hoisting loads. The average power consumption of the hoist mechanism however is considerably less than the maximum power capacity of the prime mover, the difference being more than sufficient to supply the combined average power demands of the swing and thrust mechanisms. In this instance the high pressure reservoir 24 serves as a power storage medium, to which power is supplied through the pump 25 from the prime mover, and by which energy from the prime mover, in excess of the demands of the hoist mechanism, is rendered available to operate the swing and thrust mechanisms. .The pump displacement regulating lever 27 is ordinarily so set that pump delivery is in excess of the combined average demands of the motors 39 and 39, so that a pressure approximating a predetermined maximum working pressure is normally maintained within the reservoir 24. As above pointed out however pump displacement automatically reduces as the pressure in the reservoir 24 approaches a predetermined maximum so that at such pressures the power demand of the pump upon the prime mover is reduced, and the power available forhoisting approaches the maximum power output of the. prime mover.

Various changes may be made in the embodiment of the invention hereinabove specifically described without departing from ,or sacrificing the advantages of the invention as defined in the appended claims.

I claim: I

, 1. In a power shovel, a main frame, a boom eaazss pivotally connected thereto, a dipper and handle on said boom having elevating means therefor, forward thrust mechanism for said dipper on said boom including a hydraulic motor operatively connected with said handle, hydraulic power means for said hydraulic motor on said main frame including a pressure dome and a driving motor, said driving motor also having geared operative connection with said dipperelevating means for positively actuating the same.

2. In'a power shovel, a main frame, a boom pivotally connected thereto, a dipper having a handle and flexible draft-elevating means therefor, forward thrust mechanism for said dipper on said boom including a hydraulic motor operatively connected with said handle, hydraulic power means for said hydraulic motor on said mainframe including a pressure dome and a constant speed driving motor, said motor also having geared operative connection with said dipper-elevating means for positively actuating the same.

3. In a power shovel, a base, a.turntable mounted thereon, a boom pivotally connected to said turntable, a shovel on said boom, actuating means for said shovel carried by said main frame, and means for rotating said turntable on said base including a hydraulic motor, hydraulic power means for said hydraulic motor on said main frame including a pressure dome and a constant speed driving motor, said driving motor also having direct operative connection with said shovel means for positively actuating the same.

4. In a power excavator the combination of a prime mover, hoist mechanism directly driven by said prime mover, thrust mechanism, a hydraulic pressure reservoir, a hydraulic motor driven from said pressure reservoir for driving said thrust mechanism, and a pump driven by said prime mover for maintaining, a working pressure in said reservoir.

5. In a power excavator the combination of a prime mover, hoist mechanism directly driven by said prime mover, swing mechanism, a hydraulic pressure reservoir, a hydraulic motor driven from said pressure reservoir for driving said swing mechanism, and a pump driven by said prime mover for maintaining a working pressure in said reservoir.

6. In a power shovel, a frame, a boom, a dipper; auxiliary excavating instrumentalities, a cable drum on said frame, having flexible cable connections with said dipper, a constant speed engine on said frame having optional driving connection with said cable drum, a hydraulic system including a pump driven by said engine, a high pressure line and a low pressure line, a hydraulic motor for one of said auxiliary excavating instrumentalities between said high and low pressure lines, and a pressure tank connected to said high pressure line.

WALTER FERRIS. 

